English → Latin
“efficacious” in Latin
efficāxefficacious, effectual, powerful, efficientvaleōto have strength, influence, power; to avail; to be well, healthy, sound; to be worth, be worthy
The English word efficacious itself goes back to Latin efficiō, through efficāx.
Riddle & Arnold A Copious and Critical English–Latin Lexicon, 1864
efficacious
efficax (caelius ap. Cic., Epp., and Liv.; not Cic. or Caes.; often by circumlocution with efficere, valere, vim habere). Vid. EFFECTIVE, EFFECTUAL.
Quick answer
- What is the Latin word for efficacious?
- The usual Latin words for “efficacious” are efficāx, valeō. The right choice depends on the sense; see the distinctions below.
Entry from J. E. Riddle & T. K. Arnold, A Copious and Critical English–Latin Lexicon (rev. C. Anthon, New York: Harper, 1864), digitised by Fergus J. P. Walsh, CC BY-SA 4.0; Latin markup adapted by latindictionary.co.